A storage system in which a storage apparatus (storage subsystem) and a host computer are connected via a network is known. This type of host computer has application programs located therein for performing various business activities and a storage area used in the storage apparatus is allocated to each application program.
Under the above-described circumstance, for example, logical units (LUs) formed in physical storage areas of storage units are provided from the storage apparatus to the host computer. A logical unit number (LUN) as an identifier is assigned to each logical unit and each logical unit is divided into segments, which are minimum I/O access units. A logical block address (LBA) is assigned to each segment.
The host computer can access data stored in an arbitrary storage area in a specific logical unit by sending a logical address composed of the logical unit number and the logical block address to the storage apparatus.
However, a logical unit may sometimes be deleted due to a misoperation by a user. If a logical unit is mistakenly deleted, the user needs to reset the logical unit in order to recover user data.
Meanwhile, a data processing system including a central processing unit and a plurality of external storage devices is suggested, in which a directory for managing restoration information about a deleted file(s) for each external storage device is provided, so that the execution of file deletion processing and restoration processing at a high speed can be ensured by storing restoration information in a device, where a deletion target file exists, in response to a file deletion request (see Patent Literature 1).